Apparatus of the present invention has the ability to place a fixed radar cross section a predetermined distance from a real target and to seed reentry vehicle wakes for analytical or other purposes. Injecting a predetermined number of ions and free electrons at a predetermined position in the upper atmosphere or space permits generation of a radar target, permiting calibration of ground or in-flight radars, seeding of reentry vehicle wakes to permit studies and diagnosis of wake turbulence and other wake properties.